Controversial Tory MP Nadine Dorries has said she will stop claiming parliamentary expenses

Ms Dorries, whose expenses are under investigation by the Independent Parliamentary Standards Authority (Ipsa), said she is giving up claiming from the end of next month so she can argue for reform of the system.

In a posting on her website, she said her decision would mean she would effectively be working for her constituents for free.

Ms Dorries, who shot to fame with her appearance on the TV reality show I'm A Celebrity... Get me Out Of Here! - has frequently expressed exasperation with Ipsa and the new system imposed in the wake of the MPs' expenses scandal.

Writing on her blog, she said: "I can't talk about the Ipsa investigation until it reports other than to say that so far I am happy with the way the investigation has been conducted and I am looking forward to the report.

"However, separate from the investigation, I have made the decision to stop claiming any personal MP expenses and to fund my role as an MP from my salary. In effect, this will take most of my salary, which means I will be representing Mid Bedfordshire for free!

"I have long said that under the present system, before long, Parliament will be a place of millionaires or paupers. I loathe the expenses system and believe it should be scrapped and MPs paid one flat-rate fee.

"Whilst I draw personal expenses, I cannot argue for reform of the system or put forward the case to scrap expenses. Not drawing expenses puts me in a stronger position to be able to do this.

"As someone who is high profile and frequently reported, I have also decided that it is not fair to put my staff through the constant stress that scrutiny and investigations bring about."

She strongly defended the way she had claimed expenses in the past, insisting that a second home in Westminster was "essential" for her to carry out her duties as a MP.

"I cannot fulfill my role as an MP without accommodation in Westminster. I cannot travel backwards and forwards to and from Bedfordshire on late nights," she wrote.

"For the last eight years I have claimed for the cost of my room/flat, as I am entitled to, plus council tax, utilities and my travel expenses to and from the constituency to Westminster - as do the majority of MPs.

"From the end of July I will fund this using my salary and will draw no personal expenses.

"I have rarely claimed the late night meal allowance and have never claimed the £2,800pa allowed when I was a single parent with a child under the age of 21 in full-time education."